I wish I could remember the name of the dealer he bought the boat from as their mechanic new NOTHING about wiring a boat so I would not receommend buying from them.
While our guest was out he had a problem where he couldn't get the boat to start. He ran back to the Resort on his kicker and I had a look at it. The boat had two batteries in the stern one to port and one to starboard and two up in the bow dedicated to feeding the invertor for AC power. When they wired the boat rather than using one of the stern batteries for starting and one as a house battery they just ran the wires from all the gear to the closest battery. Also, rather than running everything through a DC distribution panel, so you could diagnose and fix things quickly in an emergency, there was a mass of inline fuse holders dangling from each battery with no labels on any of the wires. Running direct is okay for things like your downriggers but his bilge pumps, lights and electronics were all run direct as well.
So what he had done was plug in one of those refridgerated coolers and killed his starting battery. I couldn't believe a dealer would wire a boat that way..... Morale of the story make sure you know what your buying even if it's from a dealer!